When a trace amount of a substance to be detected such as protein and DNA can be quantitatively detected with high sensitivity in clinical examinations or the like, it is possible to rapidly check the condition of the patient and to treat a disease. For this reason, there is a demand for a detection apparatus capable of detecting a trace amount of a substance to be detected quantitatively with high sensitivity.
As a detection apparatus capable of detecting a substance to be detected with high sensitivity, there is known a device utilizing surface plasmon resonance fluorescence spectroscopy (Surface Plasmon-field enhanced Fluorescence Spectroscopy: hereinafter, abbreviated as “SPFS”) (for example, refer to Patent Literature 1).
In the detection apparatus disclosed in Patent Literature 1, used is a sensing chip (sensor structure) having a sensor member and a well member immobilized on the sensor member. The sensor member includes a prism (dielectric member), a metal film formed on the prism, and a reaction field (ligand immobilization region) which is a region where a capturer (ligand) formed on the metal film for capturing a substance to be detected (analyte) is immobilized. The well member has a through-hole at a position corresponding to the reaction field. By arranging the well member on the sensor member, a well for storing a sample solution is formed. In the detection apparatus, the capturer captures the substance to be detected in the reaction field in the well, and the captured substance to be detected is labeled with a fluorescent substance. In this state, when the metal film is irradiated with excitation light through the prism at an angle at which surface plasmon resonance occurs, localized field light can be generated on the surface of the metal film. By the localized field light, the fluorescent substance that labels the substance to be detected captured on the metal film is selectively excited, and fluorescence light is emitted from the fluorescent substance. By detecting the fluorescence light, the detection apparatus can detect the presence or amount of the substance to be detected.
In the sensing chip, if the substance to be detected adheres to an inner wall surface of the through-hole of the well member, the detection efficiency is lowered. In order to prevent the problem, the sensing chip disclosed in Patent Literature 1 is manufactured by immobilizing the capturer on the entire surface of the metal film, and after that, arranging the well member on the metal film or by immobilizing the capturer on a portion of the surface of the metal film by using a frame member having a through-hole, and after that, removing the frame member and newly arranging the well member on the metal film. By manufacturing the sensing chip in this manner, it is possible to prevent the capturer from being immobilized on the inner wall surface of the through-hole of the well member.